Patient records from the Thiaroye mental hospital in Senegal were analyzed to see if the patterns of persons accompanying patients to the hospital could help portray the community's response to mental illness. A systematic sample of 935 records of initial out-patient visits were examined. Patterns of patient companionship were found to strongly correlate with specific patient sociodemographic and clinical characteristics. Interpretation of these findings helped to clarify both prevailing attitudes toward the mentally ill and the social response and management of mental illness. This article presents the study setting, methods, patient sociodemographic and clinical characteristics, and characteristics of patient companions. The second article in this series examines the statistical associations of companion number, gender and kinship relationship with patient sociodemographic and clinical characteristics.